get_card_balance

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations provided, so description carries full disclosure burden. It successfully documents the access control policy (same client_id restriction) and compensates for the missing output schema by listing specific return fields (available_balance, card_currency, status, updated_at). Minor gap: no error behavior described.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences total, front-loaded with purpose, followed by access constraints, then return value documentation. No filler or redundant content; every clause provides necessary information not available in structured fields.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter read tool, the description adequately compensates for missing annotations and output schema by disclosing return structure and access restrictions. Would benefit from brief mention of error behavior (e.g., card not found) to be fully complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Input schema has 100% description coverage (card_id with example format 'c_123'). Since the schema fully documents the parameter, the baseline score of 3 applies; the description does not need to add redundant parameter details.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Description opens with specific verb 'Get' and clearly identifies the resource (current balance and status of a virtual card). It implicitly distinguishes from sibling batch_card_balances (single vs. multiple cards) and get_card_details (specific balance/status focus vs. general details).

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides clear access constraint ('Only cards created by this agent (same client_id) are accessible') which establishes when the tool is applicable. However, it does not explicitly name alternatives like batch_card_balances for bulk operations or differentiate from get_card_details.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.